This invention relates to potentiometers, and in particular, to a novel manner of effectively reversing the electrical positions of terminals connected to either end of a potentiometer's resistance track.
Potentiometers of the type well known to those skilled in the art are employed in many varied applications. Such potentiometers include a resistance track having first and second terminals connected respectively to each end thereof. A wiper element is adapted for relative movement with respect to the resistance track. The wiper element is also connected to a terminal.
In some applications, both resistance track end terminals are connected to an electrical circuit whereby relative movement between the wiper element and resistance track varies the resistance between the wiper terminal and each of the resistance track end terminals. In other applications, the potentiometer is employed in the electrical circuit as a rheostat. When used as a rheostat, only a selected one of the resistance track end terminals, and the wiper terminal, are connected in the electrical circuit. When used as a rheostat, the potentiometer does not provide any resistance at a first position of the wiper element with respect to the resistance track. As a relative movement between the wiper element and resistance track occurs, the resistance of the potentiometer increases, until the potentiometer's maximum resistance is established. The wiper element has been thus moved to a second position with respect to the resistance track.
Very often, the electrical circuit in which such devices are employed requires that the resistance increase between the wiper terminal and a preselected one end terminal upon a clockwise relative movement between the wiper element and resistance track, and decrease upon a counterclockwise relative movement therebetween.
Heretofore, potentiometers have been constructed whereby maximum resistance between the wiper element terminal and a selected one of the resistance track end terminals might only be readily obtained with rotation in a preselected direction, for example, clockwise rotation. Thus, potentiometers affording maximum resistance between the wiper terminal and selected one end terminal when relative movement between the wiper element and resistance track is in a conterclockwise direction cannot be interchangeably employed with potentiometers affording maximum resistance when relative movement occurs in the clockwise direction. In many prewired applications, manuals or other literature indicate which of the two types of potentiometers are employed. Persons adjusting such potentiometers, look to the manuals for guidance in order to properly vary the resistance of the potentiometer to obtain a desired value. The utilization of potentiometers having increasing resistance when relative movement occurs in a clockwise direction, where manuals indicate that resistance increases upon relative movement in a counterclockwise direction can cause intolerable problems.
It might be thought that utilizing the other end terminal could permit a potentiometer, having a resistance increase upon clockwise movement, to be employed in applications normally using potentiometers having their resistance increase upon relative movement in the counterclockwise direction.
However, in applications involving the production of prewired circuits on a mass production basis, the two types of potentiometers cannot be readily interchanged without introducing problems and requiring expensive modifications in the assembly process.
In order to provide potentiometers suitable for use in applications requiring maximum resistance on relative movement in both clockwise or counterclockwise directions, configuration changes in the size and/or shape of one or more of the component parts has heretofore been required. For example, a "mirror image" of the complete potentiometer could be provided. Alternatively, the shape and location of te resistance track end terminals could be suitably modified. However, such changes would be expensive, involving extensive modifications to fabricating and assembly tooling and fixtures.